Growth and phenolic constituents production of roselle (Hibiscus sabdariffa var. UKMR-2) in response to soil media

Abstract

Plant phenolic content frequently varies in response to the changes in the environment and genetic factors. However, studies on the response of phenolic contents when cultivating under different soil media is still scarce. The present study investigates the phenolic constituents’ production and growth quality of Hibiscus sabdariffa var. UKMR-2 in response to different soil media formulation ratio of topsoil, organic matter and sand. The cultivation using two different media; Soil Media 1 (SM1) with 2:1:1 v/v and Soil Media 2 (SM2) with 2:1:2 v/v. The UKMR-2 calyx extract was analysed for total phenolic (TPC), total anthocyanin (TAC), antioxidant activity (in IC₅₀) and evaluated based on HPLC-PDA. The result showed the mean value for SM1 and SM2 treatment, respectively: TPC was 2.54±0.34 and 2.47±0.34 mg GAE / g DW; TAC was 8.06±1.11 and 7.86±1.99 mg cyanidin-3-glucoside equivalents / g DW; IC50 value was 0.146±0.018 and 0.210±0.063 mg/mL. The HPLC-PDA showed the presence of delphinidin-3-O-sambubioside and cyanidin-3-O-sambubioside. The cultivation using SM1 tends to increase plant growth, calyx yields, phenolic constituents’ production and antioxidant activity. However, the different soil media ratio has no significant influence on the growth and phenolic constituent production (p > 0.05). In general, SM1 (2:1:1 v/v) soil media ratio may produce better growth, higher percentage yield and phenolic constituents’ for UKMR-2 cultivation.